Common Names

Synonyms

Biostatus and Distribution

The two-spotted ladybird is an adventive species from Europe. It was first found in New Zealand in Christchurch during March 1936. It is now found throughout New Zealand though it is uncommon in Auckland. It is found in crops, parks and gardens on trees and shrubs and other plants. It feeds on aphids and other small insects, including native species.

Conservation status: This adventive ladybird is present throughout New Zealand. It feeds on native insects. It may assist with control of some aphids, psyllids and other small insects on economic and ornamental plants.

Life Stages and Annual Cycle

The red and black adults are about 5 millimetres long. This species can have several different colour forms or morphs. In New Zealand, three forms are known in addition to the typical form. In the typical form the head and prothorax (first part of the middle body) are black and white, the prothorax having a large white patch on the side and a small white patch on top. The elytra (wing covers) are red with two black spots. The melanic (dark) form in New Zealand has predominately black elytra with patches of orange red and it has reduced areas of white on the prothorax. The head is also black with two small white patches. The two other forms are red or pale orange and the pair of large spots on the elytra are irregularly shaped and there is a tiny black mark on the lateral edge of each elytrum. The underside and legs of the ladybird are black. Under the elytra is a pair of wings used for flying. The small head has a pair of compound eyes and two short antennae. The antennae are brown with a dark tip.

Female ladybirds lay pale yellow eggs near infestations of prey. A larva hatches from each egg. There are four larval instars (stages). As the larva grows, it moults (changes skin). The newly hatched larva is dark grey with black mounds with stout seta (struma, tubercles), and black legs and prothorax (first segment with legs). The second instar larva is similarly coloured though the intensity of the grey body colour is variable. The abdominal body colour of the later instars is also variable. As is the presence of pale areas on the thorax. The later larvae have some pale abdominal struma, but the intensity of the white or yellow colour is very variable. Consistently there is a pair of central struma on segment 4 (or the area between the struma is pale) and a pair of lateral struma on segment 1 are yellow-white. There are three pairs of legs. Larvae also use the tip of the abdomen for holding onto the substrate on which they are walking. The tip of the abdomen is also used for hold the larva on to a surface while moulting to a larger larva or pupa. When the fourth larval instar is fully grown, it attaches itself to a sheltered place on a plant. The pupa is a grey with dark patches on the abdomen and black wing buds. The moulted larval skin is at the base of the pupa. Adults hatch from pupae and mate. The length of time of each life stage depends on temperature, being shorter at higher temperatures.

Annual cycleThe ladybird probably overwinters as adults. Larvae have been found in spring. There are probably at least three generations per year.

Walking and flyingBoth adult and larval stages of this ladybird have three pairs of legs that can be used for walking. Larvae also use the tip of the abdomen for holding onto the substrate. Adults have wings and can fly.

FeedingThe adult and larval ladybirds eat small insects such as aphids and psyllids. The jaws are the primarily structures used for holding and chewing the prey. Legs do not appear to be used for holding food.

Recognition

The typical form of the adult two-spotted ladybird is easy to recognise with their red eylta (wing covers) with the two black spots. The melanic (dark) forms are distinctive, but they are not obviously two-spotted ladybirds. The pale forms are more like the typical adult ladybird, but in addition to their pair of irregularly shaped black spots, they also have a small black spot on the lateral edge of each elytrum.

The larvae are grey, pale or dark grey. Older larvae have pale (white or yellow) tubercles, lateral tubercles on the first abdominal segment and the pair of dorsal tubercles on abdominal segment 4. The intensity of the colour is variable and on some larvae the yellow associated with the dorsal tubercles on segment four may be restricted to the area between the tubercles.

The pupae appear dark and drab. They have a pale grey background with large black patches on the abdomen and are black elsewhere.

Natural Enemies

In New Zealand, the only predator of two-spotted ladybird known is the Shining cuckoo, Chaleites lucidus (Cuculidae). Spiders and predatory insects probably prey upon the ladybirds.

Prey/Host

Both adults and larvae of two-large spotted ladybird feed on aphids and psyllids in New Zealand. In Australia, they have been observed feeding on larvae of other species of ladybirds. They are associated with aphids on trees, shrubs and tall herbs and grasses such as sweet corn.

Additional Information

Biological control of pestsIn gardens and parks this ladybird contributes to the control of aphids, psyllids and other insects on trees, shrubs and tall herbs. For example, they can be seen in colonies of psyllids on hedges of karo, Pittosporum crassifolium.

Diverse habits of 'ladybirds'Not all ladybirds eat insects; some feed on mites. Other species eat plant leaves and are pests especially in some tropical countries, whereas other ladybirds feed on fungi. One of these, Illeis galbula (Mulsant, 1850), from Australia, feeds on powdery mildew fungi. In New Zealand it is common on pumpkins and other cucurbits, plants that are commonly infected by powdery mildews. A plant feeding ladybird, hadda beetle (Epilachna vigintioctopunctata (Fabricius, 1775)) recently established in Auckland feeds on plants in the Solanaceae (potato family).

Colour variation in two-spotted ladybirdIn Europe two-spotted ladybirds have many variations on colour patterns. These are divided into two groups, those that are red with black spots (non-melanic) and those that are mostly black with red spots (melanic). The colour pattern on each adult stays the same for the life of the adult. Research has shown that each colour form (morph) is genetically distinct. The frequency of the various morphs varies geographically and has been found to vary along clines (environmental gradients). Several ideas have been proposed to explain this variation including industrial melanisation and thermal melanisation. This latter idea proposes that in places with cool spring weather, dark coloured ladybirds absorb more heat and start breeding earlier than non-melanic morphs. De Jong and Brakefield (1998) give evidence for this in their paper.

Warning colourationThe bright colour of some ladybirds is believed to be a warning to potential predators such as birds. These brightly coloured ladybirds contain various alkaloids that may make the beetles taste unpleasant; some ladybird contains the chemical coccinelline. This chemical can deter feeding by ants and birds. Ladybirds with warning colouration also exhibit 'reflex bleeding', emitting blood containing the alkaloids.

AggregationSome ladybirds also emit another chemical, an aggregation pheromone.

Information Sources

de Jong PW, Brakefield PM 1998. Climate and change in clines for melanism in the two-spotted ladybird, Adalia bipunctata (Coleoptera: Coccinellidae). Proceedings of the Royal Society, London, B 265: 39-43.

Read DB 1965. The field recognition of the larvae of three common aphid-feeding Coccinellidae. New Zealand Entomologist 3(4): 14-17.